Self-testing insertion tool and methods of inserting workpieces

ABSTRACT

A workpiece insertion tool includes a shaft for engaging the workpiece, a housing slidably mounted on the shaft, a spacer integrally attached to the shaft, an elastic member between the housing and the spacer, and a blocking member. To insert a workpiece into a workpiece-receiving member a force is applied to the housing. The elastic member initially operates to transmit the force to the spacer and therefore to the shaft so as to apply a gradually increasing force tending to insert the workpiece. Failure of the elastic member to compress to a predetermined extent, before a predetermined movement of the workpiece into the receiving member occurs, operates to bring the blocking member into engagement with the housing to immobilize the tool and to prevent complete insertion of the workpiece. Whenever the elastic member does compress sufficiently, further force is applied to the housing and shaft to complete the insertion.

United States Patent Jack [451 June 20, 2972 [22] Filed:

[54] SELF-TESTING INSERTION TOOL AND METHODS OF INSERTING WORKPIECESRonald H. Jack, Rolling Meadows, Ill.

Teletype Corporation, Skokie, 111. Dec 29, 1969 [2]] Appl. No.: 888,730

[72] Inventor:

[73] Assignee:

5/1965 S ussman ..173 53 Primary ExaminerJohn F. Campbell AssistantExaminerDonald P. Rooney Att0mey-J. L. Landis and R. P. Miller ABSTRACTA workpiece insertion tool includes a shaft for engaging the workpiece,a housing slidably mounted on the shaft, a spacer integrally attached tothe shaft, an elastic member between the housing and the spacer, and ablocking member. To insert a workpiece into a workpiece-receiving membera force is applied to the housing. The elastic member initially operatesto transmit the force to the spacer and therefore to the shaft so as toapply a gradually increasing force tending to insert the workpiece.Failure of the elastic member to compress to a predetermined extent,before a predetermined movement of the workpiece into the receivingmember occurs, operates to bring the blocking member into engagementwith the housing to immobilize the tool and to prevent completeinsertion of the workpiece. Whenever the elastic member does compresssufficiently, further force is applied to the housing and shaft tocomplete the insertion.

SELF-TESTING INSERTION TOOL AND METHODS OF INSERTING WORKPIECESBACKGROUND OF THE INVENTION The present invention relates generally toinsertion tools and methods of inserting workpieces into aworkpiece-receiving member, and in particular to a self-testinginsertion tool which operates to immobilize itself if a predeterminedminimum force is not required to insert a workpiece.

Generally, workpiece-insertion tools of the self-testing variety aredesigned to determine that a minimum retentive force exists between apress fit workpiece and a receiving member into which the workpiece hasbeen inserted. This is done to ensure that later manipulation or jarringof the workpiece will not readily remove it from its seat. Typically,the insertion tool exerts a withdrawal force on the workpiece after ithas been seated to ensure that a predetermined minimum force will notwithdraw the workpiece from its seat. If the workpiece resists removalwhen the required minimum withdrawal force is applied, the insertiontool operates to release the workpiece; if not, the insertion toolremoves the workpiece from its seat.

Of necessity, the insertion tool must be of a complex design. Theworkpiece-engaging end of the tool must be capable of retaining a gripon the workpiece so that a withdrawal force may be exerted, and must becapable of releasing its grip on the workpiece if the workpiece resistsremoval under the minimum required withdrawal force. Also, designdetails may have to be added to a workpiece to allow the tool tomaintain a grip on it when exerting a withdrawal force, when otherwise,but for accommodating the tool, the workpiece could beof a simplerdesign.

It has been determined that the force required to withdraw a press-fitworkpiece from a receiving member is an increasing function of the forcerequired to insert the workpiece into the member. Therefore, to achievea predetermined minimum retaining force between the receiving member anda workpiece, a predetermined minimum inserting force may be establishedsuch that, if any force less than said minimum force is capable ofinserting the workpiece, it is an indication that an unacceptable pressfit would exist if the operation were completed. It is upon therelationship of said withdrawal force to said insertion force that thepresent invention is based.

A specific object of the invention is to provide a self-testinginsertion tool with which the force required to insert a workpiece intoa receiving member, rather than the withdrawal force, is used as anindication of the retentive force of the press fit. Another object is toprovide such a too] where the insertion operation may be arrestedwhenever the predetermined force condition has not been met, so as toprevent complete formation of unsatisfactory assemblies.

A further object of the invention is to provide a self-testing insertiontool having a workpiece-engaging end of a noncomplex design, such as aflat end of a shaft, and being capable of operating with workpieces ofboth a complex and a noncomplex design.

' SUMMARY OF THE INVENTION The foregoing and other objects of theinvention are accomplished by providing a member for pushing theworkpiece into a receiving member. To operate upon the workpiece, aforce is applied to the pushing member and thereby to the workpiece. Ifa predetermined minimum insertion force to push the workpiece apredetermined distance into the receiving member, to ensure adequateretention of the workpiece, is not encountered, the pushing'member isimmobilized to prevent complete insertion of the workpiece.

Preferably, the pushing member comprises a shaft for pushing theworkpiece, a housing slidably mounted on the shaft to which the force isapplied, a spacer integrally fixed to the shaft, and a coil springextended between the housing and the spacer and compressible to transmitthe force applied to the housing to the spacer. A blocking member havinga housingengaging slot is provided to immobilize the housing if theminimum insertion force is not met. The housing and the spacer normallyengage the blocking member to hold the slot of the blocking member outof engagement with the housing. When a force is applied to the housingto insert the workpiece, the housing moves toward the spacer,compressing the spring which then exerts an increasing force against thespacer tending to insert theworkpiece. If the spring force is equal toor above the minimum required workpiece-insertion force before theworkpiece has moved the predetermined distance, as a result of apredetermined travel of the housing, the device operates to maintain thehousing-engaging slot out of engagement with the housing and thereforeprevents immobilization of the tool. However, failure of the spring tocompress with a force at least equal to the minimum required insertionforce, as a result of a failure of the housing to travel thepredetermined distance prior to movement of the workpiece beyond itspredetermined distance, operates to bring the housing engaging slot intoengagement with the housing, and therefore operates to immobilize thetool and prevent insertion of the workpiece.

Other objects, advantages and features of the invention will be apparentfrom the following detailed description of specific embodiments thereof,when taken in conjunction with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION The specificembodiment of an insertion tool 10 shown in the drawings includes ashaft 11 having a sleeve 12 slidably mounted on it, and a spacer 13 witha sleeve 14 integrally attached to it. The left end of the shaft 11, asviewed in FIG. 1, operates to engage a workpiece 16 and is slidablycontained within a mounting member 17. At the other end of the shaft 11a washer 18, having a larger diameter than the sleeve 12, is maintainedbetween the sleeve 12 and two nuts 19 which are in threaded engagementwith the shaft 1 1.

A cylindrical housing 21 having an enlarged cylindrical end 22 isslidably mounted on the sleeve 12 such that the left end of the housing22, as viewed in the drawings, extends toward the spacer l3, andtherefore the workpiece 16. The housing 21 is in turn slidably supportedby a mounting member 23. A sliding spacer 24, which is slidably mountedon the shaft 1 l, is normally urged into engagement with the left end ofthe sleeve 12 by a coil spring 26 which is positioned between the spacer13 and the sliding spacer 24. A housing-engaging member 27, having aninner cylindrical chamber 28, is fixed to the housing 21, andaccommodates within the chamber 28 the washer 18, the nuts 19, and aportion of the shaft 11 and the sleeve 12. The other end of the housingengaging member is threadably attached to a drive shaft 29 which may bedriven to the right or to the left by a force applied to a handle 31. Acompressed coil spring 32 is also maintained within the chamber 28 andis positioned between the nuts 19 and the right-hand of the chamber 28.

A blocking member 33 is slidably mounted on the tool 10 with a screw 35,and at various times is urged into engagement one or more of the spacer13, the sliding spacer 24 and the enlarged cylindrical end 22 of thehousing 21 by a leaf spring 34, the leaf spring 34 being shown mostclearly in FIG. 3 of the drawings. The blocking member 33 has two slots36 and 37, the first slot 36 having a width greater than the combinedwidths of the enlarged end 22 and the sliding spacer 24, and

the slot 37 having a width greater than the width. of the spacer 13.Therefore, if the enlarged cylindrical end 22 and the sliding spacer 24are moved leftwardly as shown in FIG. 1 of the drawings into alignmentwith the slot 36, and if the spacer 13 is moved leftwardly intoalignment with the slot 37, the blocking member 33 will be urged by theleaf spring 34 upwardly such that the slot 36 will engage the enlargedcylindrical end 22 and the sliding spacer 24 and such that the slot 37will engage the spacer 13.

OPERATION In use, the shaft 11 of the tool is aligned coaxially with theworkpiece 16, such as a core, which is to be force or press fitted intoa workpiece receiving member 38. As best shown in FIG. 1 of thedrawings, when the tool 10 is in a retracted position prior to aninsertion operation, the enlarged cylindrical end 22 of the housing 21is in engagement with a flat surface 39 of the blocking member 33, andthe spacer 13 is in engagement with a flat surface 41 of the blockingmember 33, thereby preventing upward movement of the blocking member 33under the urging of the leaf spring 34.

To press fit the workpiece 16 into the receiving member 38, a force isapplied to the handle 31 by any suitable means, such as a solenoid 42,which tends to drive the shaft 11 leftwardly as shown in the drawings.The force applied by the solenoid 42 to the handle 31 is applied throughthe drive shaft 29 and the housing engaging member 27 to the housing 21,sliding the housing 21 forward to engage the sliding spacer 24 and tothereby compress the coil spring 26 between the sliding spacer 24 andthe spacer 13. In a first or testing phase of operation, the coil spring26 transfers a gradually increasing portion of the force to the spacer13, and thereby to the shaft 11 and the workpiece 16. Similarly, thecoil spring 32 operates to directly transfer a gradually increasingportion of the force applied by the drive shaft 29, to the nuts 19, andthereby to the shaft 11 and the workpiece 16. However, the coil spring32 is primarily used to return the housing 21 to a retracted positionafter an insertion operation, as will be explained later, and theinsertion force exerted on the workpiece 16 which is attributable to thespring 32 is negligible and will not hereafter be considered as asignificant force in the inserting operation.

If there is initially sufficient resistance between the workpiece 16 andthe receiving member 38 to ensure an acceptable press fit, the workpiece16 will not begin to enter the receiving member 38 when the force isfirst applied, or will enter only very slightly; but rather, the housing21 and spacer 24 will move to the left, initially compressing the spring26 between the sliding spacer 24 and the spacer 13. When the housing 21moves to the left, the enlarged cylindrical end 22 moves out ofengagement with the flat surface 39 of the blocking member 33 and movesinto engagement with the sliding spacer 24, and both the enlargedcylindrical end 22 and the sliding spacer 24 are temporarily alignedwith now slot 36 in acceptable blocking member 33. If, however, at thetime of their alignment with the slot 36 there is still sufficientworkpiece resistance between the workpiece 16 and the receiving member38 to ensure an adequate press fit, the workpiece 16 will not yet havemoved leftwardly into the receiving member 38 a significant andpredetermined distance, and therefore the shaft 11 and the spacer 13will not have moved leftwardly, and the spacer 13 will continue toengage the flat surface 41 of the blocking member 33 and hold theblocking member 33 against the urging of the leaf spring 34. Continuedleftward movement of the housing 21 operates to further compress thecoil spring 26 to apply a further increasing insertion force, until thesliding spacer 24 is brought into engagement with a flat surface 43 ofthe blocking member 33 on the opposite side of the slot 36 from the flatsurface 39, as is best shown in FIG. 2 of the drawings. At this point,the workpiece has passed the minimum force test and is not known to beacceptable for completion of the inserting operation.

Shortly after the time when the spacer 24 engages the surface 43, italso engages the sleeve 14 of the spacer 13. Thereafter there is adirect positive drive between the force applied by the solenoid 42 andthe shaft 11, and the workpiece 16 is thereafter driven into thereceiving member 38 to effect a press fit. This is the second, orinsertion, phase of the operation. As the workpiece 16 is driven intothe receiving member 38, the spacer 13 is moved into alignment with theslot 37 of the blocking member 33. However, in this instance, when thespacer 13 is in alignment with the slot 37, the blocking member 33continues to be held out by the engagement of the sliding spacer 24 withthe flat surface 43 of the blocking member 33. Insertion of theworkpiece 16 stops when the left surface of the spacer 13 engages theright surface of the mounting member 17.

As the housing engaging member 27 and the housing 21 move leftward priorto engagement of the sliding spacer 24 with the sleeve 14 of the spacer13, the progressively increasing force applied to the workpiece 16 bythe shaft 11 essentially consists of the force exerted by the coilspring 26 on the spacer 13, minus the drag force exerted on the shaft 11by a drag screw 40. The drag screw 40 is preferably made from a slightlyresilient material such as nylon and is threaded into the mountingmember 17 and into forceful engagement with the shaft 11. By adjustingthe force of the engagement of the drag screw 40 with the shaft 11, theforce to be exerted on the workpiece 16 in response to a particularforce exerted on the shaft 11 by the spacer 13 may be determined. Inother words, a predetermined compression of the spring 26 may berequired for a particular chosen force to be applied to the workpiece 16by the shaft 1 1.

The force exerted by the spring 26 may be expressed as the product ofthe distance it is compressed and its spring constant, plus anyprecompressive force which may exist in the spring while the tool 10 isin its normally retracted position. As shown in FIG. 1 of the drawings,it is necessary for the sliding spacer 24, when the tool 10 is in itsretracted position, to move a distance Y (shown as the distance betweena side 46 of the slot 36 and the left side of the sliding spacer 24)before engaging the surface 43 of the blocking member 33. Therefore, theforce exerted on the workpiece 16 by the shaft 11 at the instant thesliding spacer 24 is about to engage the surface 43 of the blockingmember 33 is equal to the product of the distance Y and the springconstant of the coil spring 26 plus any initial force exerted by thecoil spring 26 as a result of precompression when the tool 10 is in itsnormally retracted position minus the drag force exerted on the shaft 11by the drag screw 40. If the spring 26 and the force of the engagementof the drag screw 40 with the shaft 11 is chosen so that the forceexerted on the workpiece 16 when the sliding spacer 24 is about toengage the surface 43 is equal to the minimum desired insertion force toensure an acceptable press fit, then if such minimum insertion forceexists between the workpiece 16 and the receiving member 38, the shaft11 will not move significantly leftward to insert the workpiece l6, andtherefore the spacer 13 will not move out of engagement with the flatsurface 41 of the blocking member 33, until the sliding spacer 24 hasmoved into engagement with the flat surface 43 of the blocking member33. Therefore, if sufficient force is required to insert the particularworkpiece 16 a significant distance into the receiving member 38 toensure an acceptable retention force between the two parts after thepress fit has been effected, the blocking lever 33 will at all timesduring the insertion operation be prevented from moving upwardly underthe urging of the leaf spring 34 by the engagement of either the spacer13, the sliding spacer 24, or the enlarged cylindrical end portion 22 ofthe housing 21, with a surface of the blocking member 33. Thus, theblocking member 33 operates to sense whether the workpiece 16 has movedsubstantially as a result of the initial force and to permit completionof the insertion operation whenever no substantial movement hasoccurred.

To return the tool to its retracted position following the insertion ofthe workpiece 16 into the receiving member 38, the force applied by thesolenoid 42 to the handle 31 is reversed, thereby moving the drivershaft 29, the housing engaging member 27 and the housing 21 rightwardlyas shown in the drawings. As the housing 21 moves to the right, thesliding spacer 24, which is in engagement with the flat surface 43 ofthe blocking member 33 as a result of the insertion operation, moves tothe right under the urging of the spring 26 until it engages the leftend of the sleeve 12 which is being urged leftwardly by the spring 32,and held immobile against the urging of the sliding spacer 24 by thespring 32 and the drag screw 40. The sliding spacer 24 then remains inengagement with the flat surface 43 of the blocking member 33 until theenlarged cylindrical end 22 of the housing 21 has reengaged the flatsurface 39 as the housing moves rightwardly. Shortly after the enlargedcylindrical end 22 returns into engagement with the flat surface 39, theright end 44 of the housing 21 engages the flat washer 18, therebydirectly driving the shaft 11, and therefore the spacer l3 and thespacer 24 rightwardly, allowing the spacer 13 to be returned intoengagement with the flat surface 41, and forcing the sliding spacer 24out of engagement with the flat surface 43. At this point the tool 10has been returned to its normal retracted position and is ready toperform another insertion operation. During retraction of the toolrightwardly, the coil spring 32 and the drag screw 40 operated to ensurethat the shaft 1 1 would not return to its original position until theenlarged cylindrical end 22 of the housing 21 had moved into engagementwith the flat surface 39 of the blocking lever 33.

To illustrate how the tool operates to immobilize itself if anunacceptable press fit between the workpiece l6 and the receiving member38 would result from an insertion operation, assume that the forcerequired to insert the workpiece 16 into the receiving member 38the'predetermined distance is less than that required to ensure anacceptable press fit. As a force is applied by the solenoid 42 to thehandle 31 to insert the workpiece 16, the housing 21 with its enlargedcylindrical end 22 will move leftward as before, engaging the spacer 24,and a gradually increasing force will again be transmitted to theworkpiece 16 through the shaft 11. This force, as described above, is afunction of the state of compression of the coil spring 26. Ifinsufficient insertion resistance is offered by the workpiece 16 to theshaft 11, so that the workpiece 16 begins to significantly move into thereceiving member 38 before the sliding spacer 24 has moved intoengagement with the flat surface 43 of. the blocking member 33, thespacer 13 will move out of engagement with the flat surface 41 of theblocking member 33 before the sliding spacer 24 moves into engagementwith the flat surface 43 of the blocking member 33. As a result, theblocking member 33 will be urged upward by the leaf spring 34, as viewedin the drawings, to allow the enlarged cylindrical end 22 of the housing21, and the sliding spacer 24, to be accommodated within the slot 36,and to allow the spacer 13 to be accommodated within the slot 37. Thisarrests the leftward movement of the sliding spacer 24, and thereforethe tool 10, by engaging the sliding 'spacer 24 with a side 46 of theslot 36. Therefore, leftward movement of the tool will be arrested bythe time that the sliding spacer 24 has moved the distance Y, andimmobilization of the tool 10 prevents further insertion of theworkpiece 16 into the receiving material 38 and indicates what would bean unacceptable press fit if the insertion operation were completed.Thus the blocking member 33 senses that the workpiece 16 has movedsubstantially and prevents completion of the insertion operation.

Once the tool has been immobilized, it may be returned to its normallyretracted position, and the defective workpiece 16 may be removed fromits partially inserted position. Before the tool can be retracted, theblocking member is first withdrawn from its engagement with the enlargedcylindrical end 22, the sliding spacer 24, and the spacer 13. Theblocking member 33 may be withdrawn, against the urging of the leafspring 34, by any suitable means, such as a solenoid 47. Then, the toolis retracted by reversing the solenoid 42 as previously described.

While only one specific embodiment of the invention has been describedin detail, it will be obvious that various modifications may be madefrom the specific details described without departing from the spiritand scope of the invention. For example, it is not necessary for thetool 10 to be used to press fit workpieces into a workpiece receivingmember. The tool 10 may be used, for example, to apply a pushing forceto any object which must be capable of remaining immovable, or movingonly a predetermined amount, while being acted upon by a minimumpredetermined force. Also, since the minimum force to be withstood bythe object to be tested is determined by the initial state ofcompression of the spring, the spring constant of the spring, thedistance Y, and the drag force exerted on the shaft by the drag screw,means may be provided to allow varying one or more of the aforementionedthree factors in determining the minimum insertion force, to allow alarge range of minimum insertion forces to be tested by the same tool.For example, if the spacer 13 were threadably engaged with the shaft 11the position of the spacer 13 on the shaft 11 could be adjusted to varythe spring force applied and to change the position of the spacer 13with respect to the slot 37. For further control, a sliding member couldbe attached to the blocking member 33 to increase or to decrease thedistance Y which the sliding spacer 24 must travel prior to engagementwith the flat surface 43, or a clamping device could be installed on thespring 26 to clamp together two or more loops of the spring, and tothereby vary the initial precompression force provided by the spring.Also, a wide range of adjustment is provided by varying the engagingforce between the drag screw 40 and the shaft 11.

What is claimed:

1. A self-testing tool for selectively force fitting a workpiece into areceiving member if a predetermined minimum holding strength will beexceeded for the fit, which comprises:

a support; I

means, mounted on the support, for applying an initial force to theworkpiece tending to urge it into the receiving member;

means, responsive to the application of the initial force to theworkpiece, for sensing whether the workpiece has moved substantially asa result of the operation of the means for applying the initialforce;and means, responsive to the sensing means, for completing the insertionoperation whenever the sensing means indicates no substantial movement,the means for applying the initial force being constructed to apply aninitial force selected to insure that the minimum holding strength hasbeen met.

2. A tool as recited in claim 1, wherein:

the means for applying the initial force comprises a pushing memberslidably mounted on the support, and means, mounted between a portion ofthe support and the pushing member, for urging the pushing memberagainst the workpiece so as to tend to insert the workpiece;

the means for completing the insertion operation includes means, mountedin the support for engagement with the pushing member, for applyingincreased force to the pushing member; and

means are provided, mounted in the support for engagement with thepushing member, for immobilizing the pushing member in response to thesensing means if the workpiece has moved substantially as a result ofthe application of the initial force.

3. A tool for inserting a workpiece into a workpiece receiving memberthat offers resistance to such insertion, which comprises:

a support;

a member, mounted on the support, for pushing the workpiece into thereceiving member;

means, mounted on the support and engaging the pushing member, forapplying a force to the pushing member and thereby to the workpiece toinsert the workpiece into the receiving member; and

means, mounted on the support in engagement with the pushing member andresponsive to a predetermined minimum pushing force required to push theworkpiece a predetennined distance into the receiving member, forimmobilizing the pushing member if the minimum force is not encountered,so that the workpiece will not be completely inserted into the receivingmember in such a case.

4. A tool as recited in claim 3, wherein the means for immobilizing thepushing member comprises:

a blocking member mounted on the support in engagement with the pushingmember; and

means, mounted on the support and responsive to said minimum pushingforce, for moving the blocking member into blocking engagement with thepushing member.

5. A tool as recited in claim 4, wherein the pushing member comprises;

a shaft for pushing the workpiece; a housing comprising a portion of thesupport and slidably mounted on the shaft, to which the force isapplied; and an elastic member mounted between a portion of the shaftand the housing and compressible to transmit a portion of the forceapplied to the housing to the shaft,

6. A tool as recited in claim 5, wherein:

the blocking member has a surface for normally engaging a portion of thehousing, and has a slot in the surface to engage the housing toimmobilize the housing;

compression of the elastic member as a result of a force on the housinggreater than the predetermined minimum force required to insert theworkpiece into the receiving member prevents the slot in the blockingmember from engaging the housing; and

a lesser compression of the elastic member as a result of workpieceinsertion .with less than the predetermined minimum force requiredallows the housing to be engaged and immobilized by the slot in theblocking member.

7. An insertion tool, which comprises:

a support;

a housing slidably mounted on the support for longitudinal movementalong an axis;

a shaft having a portion slidably mounted within the housing forlongitudinal movement along the same axis, said shaft having a spacerfixed thereto;

means, mounted on the support, for applying a force to the housing tomove the housing in a first direction along said axis;

an elastic member mounted between the spacer and the housing andcompressible to transmit a portion of the force applied to the housingto the spacer and therefore to the shaft so as to tend to move the shaftin the same direction as the housing with a force governed by theproperties of the elastic member; and

means, mounted on the support and responsive to relative longitudinalmotion between the housing and the spacer in response to the forceapplied to the housing, for immobilizing the housing and preventingfurther movement thereof in response to the applied force.

8. A tool as recited in claim 7, wherein the elastic member comprises acoil spring.

9. A tool as recited in claim 7, wherein the means for immobilizing thehousing comprises:

a movable blocking member mounted on the support for movement toward andaway from the housing and normally positioned out of the path ofmovement of the housing; and

means mounted on the support and responsive to the relative motionbetween the housing and the spacer for moving the blocking member intoblocking engagement with the housing. 10. A tool as recited in claim 9,wherein the blocking member has a surface for normally engaging thehousing and the spacer, and has a slot in the surface to engage thehousing when the housing is immobilized.

11. A tool as recited in claim 10, wherein the simultaneous movement ofboth the housing and the spacer, as a result of the noncompression ofthe elastic member when a force is applied to the housing, allows thehousing to be engaged by the slot in the blocking member; and

wherein movement of the housing across the slot when a force is appliedto the housing, prior to movement of the spacer as a result of thecompression of the elastic member, prevents the housing from beingengaged by the slot.

UNITED. STATES PATENT' OFFICE I CERTIFICATE OF CORRECTION Patent NO.5,670,388 Dated June 20, 1972 In fl RONALD ,H. JACK It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shovm below:

Cover sheet of patent containing ABSTRACT:

Change date patent issued from "June 20, 2972" to --June 20, 1972--Signed and sealed this 9th day of July 1974.

(SEAL) Attest:

MCCOY M.GIBSON, JR C. MARSHALL DANN Attesting Officer: v Commissioner ofPatents FORM PC4050 I USCOMM-DC 60376-P69 u.s. GOVERNMENT PRINTINGOFFICE I969 o-ass-su,

1. A self-testing tool for selectively force fitting a workpiece into areceiving member if a predetermined minimum holding strength will beexceeded for the fit, which comprises: a support; means, mounted on thesupport, for applying an initial force to the workpiece tending to urgeit into the receiving member; means, responsive to the application ofthe initial force to the workpiece, for sensing whether the workpiecehas moved substantially as a result of the operation of the means forapplying the initial force; and means, responsive to the sensing means,for completing the insertion operation whenever the sensing meansindicates no substantial movement, the means for applying the initialforce being constructed to apply an initial force selected to insurethat the minimum holding strength has been met.
 2. A tool as recited inclaim 1, wherein: the means for applying the initial force comprises apushing member slidably mounted on the support, and means, mountedbetween a portion of the support and the pushing member, for urging thepushing member against the workpiece so as to tend to insert theworkpiece; the means for completing the insertion operation includesmeans, mounted in the support for engagement with the pushing member,for applying increased force to the pushing member; and means areprovided, mounted in the support for engagement with the pushing member,for immobilizing the pushing member in response to the sensing means ifthe workpiece has moved substantially as a result of the application ofthe initial force.
 3. A tool for inserting a workpiece into a workpiecereceiving member that offers resistance to such insertion, whichcomprises: a support; a member, mounted on the support, for pushing theworkpiece into the receiving member; means, mounted on the support andengaging the pushing member, for applying a force to the pushing memberand thereby to the workpiece to insert the workpiece into the receivingmember; and means, mounted on the support in engagement with the pushingmember and responsive to a predetermined minimum pushing force requiredto push the workpiece a predetermined distance into the receivingmember, for immobilizing the pushing member if the minimum force is notencountered, so that the workpiece will not be completely inserted intothe receiving member in such a case.
 4. A tool as recited in claim 3,wherein the means for immobilizing the pushing member comprises: ablocking member mounted on the support in engagement with the pushingmember; and means, mounted on the support and responsive to said minimumpushing force, for moving the blocking member into blocking engagementwith the pushing member.
 5. A tool as recited in claim 4, wherein thepushing member comprises; a shaft for pushing the workpiece; a housingcomprising a portion of the support and slidably mounted on the shaft,to which the force is applied; and an elastic member mounted between aportion of the shaft and the housing and compressible to transmit aportion of the force applied to the housing to the shaft.
 6. A tool asrecited in claim 5, wherein: the blocking member has a surface fornormally engaging a portion of the housing, and has a slot in thesurface to engage the housing to immobilize the housing; compression ofthe elastic member as a result of a force on the housing greater thanthe predetermined minimum force required to insert the workpiece intothe receiving member prevents the slot in the blocking member fromengaging the housing; and a lesser compression of the elastic member asa result of workpiece insertion with less than the predetermined minimumforce required allows the housing to be engaged And immobilized by theslot in the blocking member.
 7. An insertion tool, which comprises: asupport; a housing slidably mounted on the support for longitudinalmovement along an axis; a shaft having a portion slidably mounted withinthe housing for longitudinal movement along the same axis, said shafthaving a spacer fixed thereto; means, mounted on the support, forapplying a force to the housing to move the housing in a first directionalong said axis; an elastic member mounted between the spacer and thehousing and compressible to transmit a portion of the force applied tothe housing to the spacer and therefore to the shaft so as to tend tomove the shaft in the same direction as the housing with a forcegoverned by the properties of the elastic member; and means, mounted onthe support and responsive to relative longitudinal motion between thehousing and the spacer in response to the force applied to the housing,for immobilizing the housing and preventing further movement thereof inresponse to the applied force.
 8. A tool as recited in claim 7, whereinthe elastic member comprises a coil spring.
 9. A tool as recited inclaim 7, wherein the means for immobilizIng the housing comprises: amovable blocking member mounted on the support for movement toward andaway from the housing and normally positioned out of the path ofmovement of the housing; and means mounted on the support and responsiveto the relative motion between the housing and the spacer for moving theblocking member into blocking engagement with the housing.
 10. A tool asrecited in claim 9, wherein the blocking member has a surface fornormally engaging the housing and the spacer, and has a slot in thesurface to engage the housing when the housing is immobilized.
 11. Atool as recited in claim 10, wherein the simultaneous movement of boththe housing and the spacer, as a result of the noncompression of theelastic member when a force is applied to the housing, allows thehousing to be engaged by the slot in the blocking member; and whereinmovement of the housing across the slot when a force is applied to thehousing, prior to movement of the spacer as a result of the compressionof the elastic member, prevents the housing from being engaged by theslot.